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Bruce Tomlin

The 7800 cartridge board thread

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There's a couple of spots where two traces seem to merge (red to the right of the center hole & blue to the right of the middle socket). I'm assuming this is intentional or a glitch in the graphic.

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There's a couple of spots where two traces seem to merge (red to the right of the center hole & blue to the right of the middle socket).  I'm assuming this is intentional or a glitch in the graphic.
Oh no! And I was sooooo hoping that I could get boards made from a GIF of a screen capture.

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I just got the second run of mini-Ultra boards. The total of overdelivery was two boards, which were routed with a much bigger drill (it must have taken up all of the 20mil dimension distance), which made them slightly smaller than the regular boards, and they still had a bit of the panelization stumps sticking out. I could just barely see the panelization stump areas on two of the regular boards. This may be worth the extra five bucks just to see what kind of routing tolerances the board has.

 

Even though I accidentally made the two notches be different heights, the shorter one is still within spec when comparing it to a regular 7800 cartridge board. I still need to check it with actual cartridge shells, and build up a couple of them, but it looks like I've got it right this time.

 

The biggie board, however, looks like it will cost at least twice as much, just because of its size. I might could reduce the prototyping cost a bit if I could panelize them, but two of them don't fit within the working area of the free/light version of Eagle. A big manufacturer could panelize them for me, so it probably won't be as much of a problem there, but it will still probably cost twice as much as a smaller board would have from any given manufacturer.

 

EDIT: I stuck them in an old-style door cartrdige shell (minus the door, which doesn't have a wide enough slot) and a new-style 7800 cartridge shell, and they fit just a little loosely. In the newer-style cart, it actually rattled. The overdelivery boards fall right off the mounting points like my first run boards. So I'll probably tweak the neck dimensions just a hair larger for the production run.

Edited by Bruce Tomlin

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I built up one of the extra boards, and just in case it made a difference, I cut a trace and grounded the CE pin. Does anyone have any idea why I can't get an Intel 28F010/28F001 to work in this? The 28F010 chips will show the ATARI startup, but won't even show the menu screen. I looked at the 28F010 spec sheet, and the read timing doesn't seem to be any different from an EPROM. WE and VPP are jumpered to VCC, which should keep the chip from going into command mode. I've got a stack of 'em, and it would be nice to use some of them.

 

An Atmel 29C010A almost works, except when the Maria is trying to access graphics. With CE grounded, Xenophobe plays, but some of the graphics flicker regularly, and on the old board with CE connected to OE, it crashes when the game starts.

 

Another random thing: Albert wants purple soldermask. I had just re-read my transcript of Curt's 7800 history panel before he mentioned this, so I knew exactly what he meant. Unfortunately, purple is not a standard soldermask color, and sometimes you even don't get to choose anything but green. Hopefully a mix of red and blue will work, but who knows exactly what color will result.

 

So maybe I'll make a big leap, skip the 200-part pcb-pool run, and go for some place that needs Gerber files. It'll delay me by at least a week to be sure I've got it right, but in the end it'll be a good thing.

 

And at some point, I plan to release Cadsoft Eagle library files for various types of cartridge boards. So far I've made 7800, 2600, and Colecovision. Just the outlines, so people can make their own stuff. I've been learning a lot of things about Eagle library files since that first night when I barely hacked up something with the 32 edge connector pads, and now the 7800 library is pretty spiffy.

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I built up one of the extra boards, and just in case it made a difference, I cut a trace and grounded the CE pin.  Does anyone have any idea why I can't get an Intel 28F010/28F001 to work in this? The 28F010 chips will show the ATARI startup, but won't even show the menu screen.  I looked at the 28F010 spec sheet, and the read timing doesn't seem to be any different from an EPROM.  WE and VPP are jumpered to VCC, which should keep the chip from going into command mode.  I've got a stack of 'em, and it would be nice to use some of them.

 

How is the rest of your board configured ? Do you have OE* tied low at the same time, or is it tied to an enable signal (like A15* or similar) ? If it's connected to an inverted version of R/W* you will have data bus conflicts when the CPU is trying to read from outside the FLASH area. This will cause the unit to crash.

 

If you have it connected to a chip select signal (such as A15* or similar) it should really work, in that case i haven't got a clue :( A recent schematic and a description of your configuration would help.

 

Another random thing: Albert wants purple soldermask. I had just re-read my transcript of Curt's 7800 history panel before he mentioned this, so I knew exactly what he meant. Unfortunately, purple is not a standard soldermask color, and sometimes you even don't get to choose anything but green. Hopefully a mix of red and blue will work, but who knows exactly what color will result.

 

I have a contact with a chinese company that manufactures excellent PCB boards with any soldermask color that you want. Good pricing as well. Small volumes such as 200 pcs is no problemos with them either. let me know if you're interested.

 

/Pontus

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See earlier messages for the equations, but OE is based on A14, A15, and R/W. And it works great with EPROMs. With WE pulled high, these flash chips should act basically like an EPROM, and the spec sheet on the 28F010 shows read access times similar to EPROM. It's clearly a timing problem (I think I got one 28F010 to barely show the title screen), but I can't figure what's causing it.

 

As for board stuff, go ahead and PM me, but right now I'm working on getting my Gerber files together. A big problem was when I found out that Eagle's Gerberizer always outputs text using the vector font, which is not only ugly and too thin for some fab shops, but it doesn't have a copyright symbol. So I made an Eagle library of nothing but line-art text characters. I still need to tweak the silkscreen lines on some of the standard library symbols.

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All hail Kevtris!

 

He knew this bit of trivia about flash chips: you have to pulse the CE line to get them to work right. Sure, it's going up and down in the sample read cycle in the data sheet, but it doesn't actually say anywhere that you have to bring it high between reads.

 

All it took was adding "& CLK2" to both terms of the ROMCS equation, and it worked fine with a 28F010. It's a good thing I didn't feel right about grounding the CE pin.

Edited by Bruce Tomlin

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All hail Kevtris!

 

He knew this bit of trivia about flash chips:  you have to pulse the CE line to get them to work right.  Sure, it's going up and down in the sample read cycle in the data sheet, but it doesn't actually say anywhere that you have to bring it high between reads.

 

All it took was adding "& CLK2" to both terms of the ROMCS equation, and it worked fine with a 28F010.  It's a good thing I didn't feel right about grounding the CE pin.

922857[/snapback]

 

I'm just thinking out loud here. If I connect A15 through an inverter to CE* of a 28F010 and tie OE* through another inverter to the R/W* signal of a 6502 and then execute 256 NOP's from the FLASH, would it work ?? The A15 signal will stay high through all these 256 opcodes thus eliminating any pulses to the CE* pin !?

 

This is interesting, i will have to look more into this.

 

/P

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Bruce,

Any news on these boards, me want a couple to play with ;-)

 

/P

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All it took was adding "& CLK2" to both terms of the ROMCS equation, and it worked fine with a 28F010.  It's a good thing I didn't feel right about grounding the CE pin.

922857[/snapback]

 

It's also important to note that while RAM devices don't mind if /OE is strapped low during write cycles (indeed, it's not uncommon for 6502-based boards to strap /OE low and use /CE timing to gate reads) flash devices will not accept writes if /OE is low.

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Been a while now, any news on a date of release or confirmation this project is still going to be put into production?

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I want to get things going eventually, but there's an anime convention next week so I'm not going to do it right away.

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What I really want first is a no frills board that can do the maximim non bank-switched size (40 or 48K but could live with 32) so Beef Drop and the game that is a fairly obvious Q*bert knockoff can be released. Also if someone has a large stash of 7800 carts and I could come up with an efficient procedure for hacking them I would go that route (I know that would be a royal pain). Unfornately buying anything on ebay these day would be price prohibitive.

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What I really want first is a no frills board that can do the maximim non bank-switched size (40 or 48K but could live with 32) so Beef Drop and the game that is a fairly obvious Q*bert knockoff can be released. Also if someone has a large stash of 7800 carts and I could come up with an efficient procedure for hacking them I would go that route (I know that would be a royal pain). Unfornately buying anything on ebay these day would be price prohibitive.

 

You can get 7800 boards that would suit your needs, that also come with inverters so all you have to do is remove the ROM and instert your EPROM from Ebay for $3 dollars each or less in large quantity (12 or more carts). If you get a box full (72 carts) it goes down to like $2.50 each. user name is "gamesandstuff" and they have what seems and enless suply (I think they grabbed tons from O'shea's WAY back when they where 80 cents each). But ya recycling JINKS or Dark Chambers or Hat Trick, ect. Any of the 565 of 535 series boards would do the trick for you and will actually be cheaper than new PCB's I think.

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Yep, I concurr. I've dealt with them as well, and it is kind of cool getting a board and cartridge shell for that price. The only drawback is having to de-solder the chip, but that's pretty minor (if you have a solder-sucker) :)

 

Bob

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There is actually a PDF on the net of the 32K board variation that supports EPROMs. I was taking that and kind of converting it into a more usable PCB. But then this project came around and I dropped it. My main idea something like the krokodile cart where it used the PCB for the side prongs to allow the cart to go in.

 

Corey

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There is actually a PDF on the net of the 32K board variation that supports EPROMs. I was taking that and kind of converting it into a more usable PCB. But then this project came around and I dropped it. My main idea something like the krokodile cart where it used the PCB for the side prongs to allow the cart to go in.

 

Corey

I don't even mine paying to get the boards made. I could probably layout and route traces but getting the boards cut right, etc and getting files in the format that can be used to produce them is beyond me at this point. There was the simple board in the thread, but I am not sure if the final version worked plus it is copyrighted so I would probably have to start from scratch.

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I don't even mine paying to get the boards made. I could probably layout and route traces but getting the boards cut right, etc and getting files in the format that can be used to produce them is beyond me at this point. There was the simple board in the thread, but I am not sure if the final version worked plus it is copyrighted so I would probably have to start from scratch.

The board I was working on was actually to work in Atari 2600 cases. Because of the internal layout, I moved the chips at the top so the PCB protector could be removed. Just never finished moving the traces around to compensate. Maybe I will forward to a friend and see if he can figure it out.

 

Corey

Edited by 8bitclassics

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I can finally can play Beef Drop on the real thing not using a CC2. Ok, so a Ball Blazer cart had to die to make this possible but I do have pokey sound. I did have to make a minor little hack to use a 7400 instead of a 7404 since I didnt have any on hand. It is not particularly fun to do, and I don't think people would want to pay what I would charge recycling boards, but I suppose it is a doable possibility.

post-4263-1150502861_thumb.jpg

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Yes, I had done something very similar with Beef Drop and Frogger, except that I had a 7404. Those carts work *wonderful* with that setup of those two games.

 

I wish I would have known you were going to do it that way; I would have either sent you the boards or done it for you to save you the trouble.

 

Bob

Edited by PacManPlus

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